Abstract

The objective of the present study was to obtain information on prostaglandin (PG) biosynthesis in placenta following narcotic administration. PG biosynthetic capacity was determined in whole rat placenta homogenates in the presence of Na arachidonate, by evaluating net production of PGs assayed against PGE1 on rat stomach strips.

An enhanced prostaglandin-like activity is shown in homogenates of placenta from rats treated subcutaneously with 10 mg/kg of morphine.This increase was prevented by naloxone pre-treatment.

Continual morphine administration during gestation, results in a normalization of placental biosynthetic capacity thus suggesting the development of a tolerance to the narcotic effect.